1. Field of the Invention
The present invention relates to a method of attaching a mold releasing agent to various molding dies and a molding apparatus or, in particular, to a method of attaching a mold releasing agent to various molding dies and a molding die used for molding a magnesium alloy.
2. Description of the Related Art
In molding various molding materials using a molding die, a mold releasing agent is coated, in advance, on the surface of the molding cavity of the molding die, the material supply path for supplying the molten molding material and the surfaces of the molding die contacted by the molding material to thereby facilitate the moval of the molded product after opening the die.
In the prior art, as shown in FIG. 11, with the molding die 9 full open and thus the material contacting surfaces 900 exposed, the mold releasing agent 930 is coated by spraying a stock solution of the mold releasing agent, diluted with water, directly by a spray 93 between a fixed die 91 and a movable die 92.
According to this conventional method, a lubrication film 931 is formed by the mold releasing agent 930 on the material contacting surfaces 900 and the molding die 9 is cooled by the mold releasing agent.
In the case where the molding die 9 is temperature regulated, the molding die 9 is excessively cooled and the temperature restoration time is increased and the run of the molten material is deteriorated, resulting in a deteriorated appearance quality of the molded product and an increased rejection rate of the molded product. This problem becomes conspicuous especially in molding a magnesium alloy having a small heat capacity.
Also, excessive application of thermal stress to the molding die 9 shortens the service life of the molding die 9 due to metal fatigue.
Further, a considerable length of time is required for uniformly spraying the mold releasing agent 930 on the material contacting surfaces 900. In addition, an air blow process is required for drying the residual mold releasing agent 930. The conventional method of spraying the mold releasing agent 930 thus requires a considerable working time, and therefore constitutes a factor causing a lengthened molding cycle time.
Furthermore, the sprayed mold releasing agent 930 is scattered or drips off outside of the molding die 935, thereby adversely affecting the working environment.
Another problem is that, as shown in FIG. 11, the mold releasing agent 930 attaches to the dividing surfaces 901 of the fixed die 91 and the movable die 92 not constituting the material contacting surface 900.
Especially when the mold releasing agent 930 attaches to the dividing surfaces 901, burs or the like, generated at the time of molding, attach to the fixed die 91 and the movable die 92, which are thus improperly closed often causing a molding failure.
The present invention has been achieved in view of the aforementioned problems of the prior art, and the object thereof is to provide a method of attaching a mold releasing agent to a molding die, a molding apparatus and a molding die which prevent the excessive cooling of the molding die, shorten the molding cycle time and prevent the deterioration of the working environment, while at the same time lengthening the service life of the molding die.
According to one aspect of the invention, there is provided a method of attaching a mold releasing agent to a molding die of a molding apparatus,
wherein the molding die includes at least a fixed die and a movable die configured to form a molding cavity when closed,
wherein the molding cavity is connected to a nozzle receiving surface facing a material supplying nozzle configured to supply a molding material from the molding apparatus,
wherein the mold releasing agent is attached to the material contacting surfaces of the molding die contacted by the molding material at the time of molding the molding material using the molding apparatus, and
wherein the fixed die and the movable die are arranged in opposed relation to each other with a gap therebetween less than a gap capable of releasing the molded product, and the mold releasing agent is supplied to the material contacting surfaces through the gap between the material supplying nozzle and the nozzle receiving surface.
What is most noticeable in this aspect of the invention is that the fixed die and the movable die are arranged in opposed relation to each other with a gap therebetween less than a gap capable of releasing the molded product, and the mold releasing agent is supplied through the gap between the material supplying nozzle and the nozzle receiving surface thereby to attach the mold releasing agent to the material contacting surfaces.
The distance capable of releasing the molded product is defined as the narrowest distance allowing removal of the molded product after the molding process, and is uniquely determined for each molding die.
By attaching the mold releasing agent to the fixed die and the movable die arranged in this way, the mold releasing agent can be prevented from attaching to the dividing surfaces of the fixed and movable dies where the mold releasing die is not required, or a lesser amount of the mold releasing agent is attached. Also, the scattering or dripping off of the mold releasing agent outside of the fixed die and the movable die can be prevented or reduced.
According to another aspect of the invention, there is provided a molding apparatus comprising a molding die,
wherein the molding die includes at least a fixed die and a movable die configured to form a molding cavity by being closed, and
wherein the molding cavity is connected to a nozzle receiving surface facing a material supplying nozzle configured to supply a molding material from the molding apparatus,
the apparatus comprising a releasing agent supply path for supplying the mold releasing agent through a gap between the material supplying nozzle and the nozzle receiving surface to the material contacting surfaces of the molding die contacted by the molding material when molding the molding material using the molding apparatus, the mold releasing agent being adapted to attach to the material contacting surfaces.
In the molding apparatus according to this aspect of the invention, the mold releasing agent is supplied along the releasing supply path from the gap between the material supplying nozzle and the nozzle receiving surface and thus can enter the molding cavity.
The material contacting surfaces are those surfaces brought into contact with the molding materials at the time of molding, and are configured of the wall surfaces surrounding the molding cavity. With the apparatus according to this aspect of the invention, therefore, the releasing agent is rarely attached to other than the material contacting surfaces.
The use of the molding apparatus according to this aspect of the invention thus makes it possible to prevent wasteful use of the mold releasing agent on the one hand and to use the stock solution, free of water for diluting the mold releasing agent, on the other. Also, a smaller amount of water is used for diluting the mold releasing agent than in the prior art.
As a result, the temperature drop, which otherwise might be caused, when attaching the mold releasing agent to the molding die, can be prevented and a molding die securing a superior run can be obtained. Also, the improved run can improve the appearance quality and reduce the rejection rate of the molded product.
Also, since an excessive thermal stress on the molding die can be reduced, the service life of the molding die can be lengthened.
Further, with the molding apparatus according to this aspect of the invention, less mold releasing agent is scattered or drips out of the molding die, and therefore the working environment is rarely deteriorated.
As a result, a shorter time is required for attaching the mold releasing agent, and so is the time required for an air blow to dry the molding releasing agent attached. Thus, the molding cycle time can be shortened.
In this aspect of the invention, as described above, a molding apparatus is provided in which the excessive cooling of the molding die is prevented, the molding cycle time is shortened, and the working environment is not deteriorated while at the same time lengthening the service life of the molding die.
According to still another aspect of the invention, there is provided a method of attaching a mold releasing agent to a molding die comprising at least a fixed die and a movable die for molding a magnesium alloy, wherein with the fixed die and the movable die arranged in opposed relation to each other with a space therebetween of less than such a distance as to be capable of releasing the molded product, the mold releasing agent is attached to the material contacting surfaces of the fixed die and the movable die.
According to a further aspect of the invention, there is provided a molding die comprising at least a fixed die and a movable die for molding a magnesium alloy, wherein at least a selected one of the fixed die and the movable die is formed with a releasing agent supply path communicating with the material contacting surfaces of the fixed die and the movable die, the molding die further comprising a support mechanism capable of supporting the fixed die and the movable die with a space therebetween of less than a space capable of releasing the molded product.
The present invention may be more fully understood from the description of preferred embodiments of the invention set forth below, together with the accompanying drawings.